1. Field of the Invention
This invention relates generally to connectors used with optical components. More particularly, it relates to connectors which may be sealed to components by fusing.
2. General Background and Related Art
For joining optical components together, or for incorporation of optical components into other devices, it is often desirable to make use of a ferrule. A ferrule is a piece of glass, ceramic, plastic or metal material having one or more holes into which components such as optical fibers may be inserted. Ferrules offer additional structural strength and support to the fiber as well as facilitating alignment of a fiber with another component.
In addition to optical applications, ferrules may find uses in applications such as joining of capillaries or other components.
In many cases it is desirable to provide a seal to prevent migration of oxygen or other contamination from the environment into a package intended to isolate an active device such as a semiconductor laser or photodetector. In other cases, a fiber must pass through a bulkhead, for example on a mobile platform or in a chemical reactor. A ferrule may also act as a heat sink or power block when a fiber is used in a high power coupling application such as a medical laser delivery system. In other cases, it is important to minimize stress induced by thermal expansion mismatches between the ferrule, bonding adhesive, and inserted optical fiber. The stresses generated by the expansion mismatch can degrade optical and mechanical performance of the overall package. Likewise, ferrules are employed in the construction of modular components which must be conveniently connected and disconnected while maintaining good alignment between fibers and other components.
It has been known in the art to seal fibers to ferrules by several methods including epoxies, metalization of the fiber or by swaging material around the fiber. Some attempts have been made to seal fibers by fusing the fiber together with the ferrule. These have had limited success as the seal generally fails to hold, or the fiber and/or the ferrule fails, particularly when fiber and ferrule are of differing materials. Even if each is made of glass, for example, fusing tends to distort the fiber to such,an extent that the fiber""s optical characteristics are changed. In the case of single mode or polarization maintaining fibers, the fiber geometry is crucial to its proper operation. Likewise, the small diameter of both core and cladding, and in the case of polarization maintaining fibers, the precise stress distributions, are extremely difficult to maintain during a fusing operation. Moreover, fusing tends to produce stress within the structure of the fiber and the ferrule which may lead to premature failure.
The present invention provides ferrules and methods for using ferrules which are adapted to be fused to optical fibers and other components.
A ferrule according to an embodiment of the present invention includes an interior wall defining at least one hole, at least a portion of the interior wall comprising a layer preferentially softenable relative to the remainder of the ferrule.
A ferrule according to an embodiment of the present invention includes a ferrule having an interior wall defining at least one hole, at least a portion of the interior wall comprising a layer preferentially softenable relative to the remainder of the ferrule, a capillary tube disposed at least partially within the hole and fused to the ferrule by at least partially softening the layer.
A fiber Bragg grating device according to an embodiment of the present invention includes a ferrule having an interior wall defining at least one hole, at least a portion of the interior wall comprising a layer preferentially softenable relative to the remainder of the ferrule, a fiber including a Bragg grating disposed within at least one hole of the ferrule and fused to the ferrule by at least partially softening the layer.
A method according to an embodiment of the present invention includes fusing an optical fiber into a ferrule having an interior wall defining a hole, at least a portion of the interior wall comprising a layer preferentially softenable relative to the remainder of the ferrule, including disposing a portion of the optical fiber within the hole, heating the layer such that at least a portion softens and flows between the interior wall and the optical fiber, allowing the softened portion to solidify to form a fused region between the ferrule and the optical fiber.
A method of manufacture according to an embodiment of the present invention includes providing a preform including an interior wall defining at least one hole, depositing a material preferentially softenable relative to the preform onto the interior wall, drawing the preform, and cutting the drawn preform to form a plurality of ferrules.
A method of manufacture according to an embodiment of the present invention includes providing a tubular member including an interior wall defining a hole, depositing a material preferentially softenable relative to the tubular member onto the interior wall by chemical vapor deposition, and cutting the tubular member to form a plurality of ferrules.